Hot-air heater



Aug. 31, 1943. w. H. RICHARDS HOT AIR HEATER Filed April 18, 1941 Axe/5 Patented Aug. 31, 1943 HOT-AIR HEATER William 11-. Richards, Dayton, Ohio Application April 18, 1941, Serial No. 389,201

Claims.

(Granted under the act 01' March a, 1883, as amended April so, 1928; 370 o. G. 751) The invention described herein may be manuiactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to an improved form of hot-air heater and more particularly to a heater of the portable type which may be used on trailers or other ambulatory vehicles.

The primary object of this invention is to provide a small, compact heater of large heating capacity which may be operated by a gasoline blow torch of conventional design.

Another object is to provide a hot-air heater of suitable design for use on the outside of a photographic trailer or other vehicle containing inflammable or explosive material.

Still a further object is the provision of a hotair heater which is readily removable from the,

compartment to be heated.

With the above and other objects in view which will be apparent from the following description, the invention consists in the construction and arrangement of parts hereinafter set forth and claimed with the understanding that the elements comprising my invention may be varied in construction, proportions and arrangement without departing from the spirit and scope of the appended claims.

In the drawing:

Fig. 1 is a sectional elevation through one form of the heater with the burner omitted.

Fig. 2 is a sectional elevation through a modifled form of the heater with the burner in place.

My improved heater is of very simple construction being composed of several sheet metal jackets or shells of cylindrical or conical form which can be easily and rapidly assembled together. They may then be fastened in place with screws or rivets or by welding where a permanent attachment is desired. A burner is detachably mounted in the base of the heater where it is readily accessible for replacement or repair. may be any gasoline blow torch of suitable design and the details thereof are not shown in the present disclosure. Above the burner is a flame spreader for expanding and distending the flame of the torch in order to better utilize its heat before it passes out of the flue. This flue is provided with fins to aid in transmitting the heat from the hot flue to the air being heated. The

air is either forced through the heater by a blower or else drawn through it by a suction fan, the blower or fan being of any suitable type.

The heater will now be described in detail.

This burner Considering first the form embodied in Fig. 1

of the drawing, l is a cylindrical sheet-metal jacket which forms a housing for the heater. This jacket is surmounted by a conically shaped piece 2 which encloses the top of the heater. A cap 3 fitting over the piece 2 facilitates the assemblage of this piece over the flue l3 and the' hot air outlet 23. The bottom edge of the jacket I is crimped around the lower edge of a supporting ring 4 so as to rigidly secure this ring within the jacket. The ring is formed with a flange 5 on the upper surface of which is seated the conically shaped fire jacket 6 and from the under surface of which is suspended a cylindrical shell 1 provided with a bottom cover 8. A hole 9 is pierced in cover 8 to permit entrance of the nozzle ID of the burner I i (see Fig. 2) into the combustion chamber formed by the parts 8 l and 8. The shell I is provided with holes It to provide the necessary air for the proper combustion of the flame from the burner.

The fire jacket 6 is surmounted by a flue I3 which conveys the products of combustion from the combustion chamber out into the atmosphere. A flame spreader I4 is suspended in the combustion chamber above the burner by a rod I5. This rod is guided through the center ofthe flue by two eye supports l5 attached to the inner wall of the flue. The upper end of this rod is threaded and carries a spacing sleeve 11, a damper l8 and two adjusting nuts I9. The bot tom edge of the spacing sleeve rests on the upper eye support l6 while the damper reclines on the top edge of the sleeve. The vertical position of the flame spreader may be varied by adjustment of the nuts l9 while the height of the damper above the end of the flue may be adjusted by using sleeves of different lengths.

. The purpose of the flame spreader is to separate and expand the burner flame which would otherwise travel up through the combustion chamber and out of the flue as a narrow column of intensely hot gases. This would result in most of the heat from the burner passing directly out of the flue which is obviously undesirable. The flame spreader prevents this direct exit of the flame and causes it to spread out and to impinge upon the walls of the jacket 6 thus heating these walls to a high degree of temperature. The damper I8 is placed over the top' of the flue to provide additional impedance to the exit of the flame so as to retain it for a longer period of time in the combustion chamber. This gives the flame more opportunity to give up its heat to the walls of the combustion chamber during its passage therethrough.

Surrounding the jacket 6 is another conically shaped jacket which is screwed or riveted to the outer jacket asat 2|. Fastened to the top of jacket 23 is a shell 22 having the form of a. segment of a toroid which serves to connect the hot air outlet pipe 23 with the jacket 20. Surrounding the pipe 23 is a cylindrically shaped casing 24 which is fastened to the piece 2. A ring 25 welded on the end of casing 24 fits snugly around the end of pipe 23 and seals the interior of jacket I from the outside air.

A cold air inlet 28 is provided near the bottom of the heater and is provided with a butterfly valve 21 which is adjustable by the hand knob 28. This inlet is in the form of a short pipe of circular cross section which is welded into the jacket I and which extends a short distance within the jacket 20.

Either a blower or a suction fan is used to force the air to be heated through the heater. If a blower is used, it is connected to the inlet pipe 26 where it forces the cold air up through the space between the jackets 6 and 23 and out through the pipe 23. If a suction fan such as that shown at 39 in Figure 2 is used, it is attached to the outlet pipe 23 where it draws the cold air in through the pipe 26, up through the heating chamber, and out through the pipe 23,

The heating chamber, which comprises the space between jackets 6 and 2B, is obstructed by baiiies 29, and 3! which cause the air proceeding up through the chamber to follow a zigzag course. therethrough. These bafiles are circular rings which completely seal the space between the walls 6 and 20 with the exception of y staggered openings in the bafiles which allow the air to pass up into the next bailled space. The

' opening in the bottom baflie 29 is on the side of the heater opposite the inlet 26. The opening in the middle bafiie 30 is on the same side of the heater as inlet 26 while the opening in the top baiile 3i is on the side opposite the outlet pipe 23. Thus the air is forced to pass from one side of the heater to the other during its upward travel so that it thoroughly scrub the walls of jacket 6 and the flue l3.

' Since the flue will be quite hot from the products of combustion passing through it, the outer surface of the flue is supplied with fins 32 over which the air must pass on its way into the outlet pipe 23. This will result in an additional amount of heat being imparted to the air before it leaves the heater.

In case it is desired to heat the air to a higher degree of temperature, means are provided for preheating the cold air supply before it is sent through the heating chamber. This is accomplished by means of four rectangular openings 33 in the outer casing which are normally covered by a metal band 34 which is rotatable around the casing. This band is provided with four openings which are of the same shape and size as those in the casing and which are similarly spaced" around the circumference of the heater. When it is desired to pre-heat the air before its entrance into the heating chamber, the band 34 is rotated until the holes in the band register with those in the casing and the butterfly valve 21 is closed. The air is now drawn in through the holes 33 instead of through the inlet pipe 26, it being understood that this feature can be used only when a suction fan is employed at the outlet instead of a blower at the inlet. The air then passes downward between the casing I and the jacket 29 until it reaches the lower edge of the .latter when it is free to pass up through the heating chamber. The passage of the air downward over the wall 20 serves to warm the air before it is passed up through the heater in the normal fashion.

The particular heater here illustrated is designed for mounting on the outside wall of a trailer. To this end holes are provided in the trailer wall to accommodate the leg 35 and the outlet pipe 23. The heater is attached to the trailer by inserting the leg and the pipe in their respective holes in the trailer wall and then fastening the clip 36 to a suitable anchorage on the trailer. The spring 31 holds the heater firmly but resiliently in place with the flanges on the legs and on the outlet pipe fitted snugly up against the wall,

The heater is entirely on the outside of the compartment to be heated and there is no opportunity for any flame or sparks to reach the inside of the trailer. Only the heated air may pass inside of the vehicle and all danger from fire or explosion is therefore removed.

If the heater is to be used in dusty or unclean air, an air filter or air cleaner may be placed over the air inlet 26 to insure that only pure, clean air will reach the inside of the trailer.

The amount of heat supplied by the heater may be controlled either by adjustment of the burner flame or by manipulation of the band 33 and the damper 21 so as to cause or eliminate pre-heating of the air supply.-

The modified form of heater shown in Fig. 2 is much the same as the one just described with the exception of the flame spreader. As shown in Fig. 2 the flame spreader 4B is hollow, being constructed of two sheet metal cones joined along their bases. The top of the flame spreader is joined to an elbowed pipe M which leads into the heating chamber adjacent the hot air outlet pipe 23. Joined to one side of the lower cone of the flame spreader is another elbowed pipe 32 which passes through a hole in the jacket 6 and into the heating chamber. Mounted in the wall of the casing l opposite the end of pipe 62 is a cold air inlet pipe illsimilar to the inlet pipe 26 but without a butterfly valve. This inlet pipe communicates directly with the heating chamber formed between jackets 6 and 20. A pin 3 3 is mounted in the bottom of the flame spreader and projects upwardly through the interior of the spreader as shown, Three perforated plates 65 are placed on the inside of the lower cone, these plates being welded to the right-hand wall of this cone. The purpose of the pin it and the plates 45 will be disclosed later on in the description. The heater of Figure 2 is mounted on the outside of the trailer wall in the same manner as the heater of Figure l, the ends of pipes 23' venience, the heater operating equally as well with a. blower as with a fan.

The flame from the burner ll impinges on the flame spreader, as before, and is thereby expanded and caused "to impinge against the walls of the acket 6. The products of combustion then proceed up the flue l3 and out into the atmosphere. A damper is not necessary in this case since the size of the flame spreader and the presence of pipes 4| and 42 offer suificient obstruction to the passage of the gases as to eliminate the need of any constriction in the flue.

The cold air to beheated is drawn into the heater through the inlet pipe 43. Part of this air will pass up through the heating chamber formed by the space between the jackets 6 and 20 which chamber isbafiied as in the previous case. The remainder-of the air will be drawn through the pipe 42 into the interior of the flame spreader and thence out through the pipe 4| into the outlet duct 23. Thus, the intense heat given to the flame spreader as a result of the flame from the burner impinging directly thereon is transmitted to the air passing through the interior of the spreader. This results in'a very efficient operation of the heater. The-perforated plates 45 are provided to dissipate the heat from the righthand wall of the lower cone of the spreader.

The relatively cool air coming into the flame spreader through the inlet pipe 43 and the pipe 42, flows over these plates and absorbs the heat from them. The pin 44 is provided for a similar purpose, the bottom tip of the spreader being subjected to the most intense heat of the flame. As the air passes up through the interior of the flame spreader it scrubs off thepin 44 and absorbs the heat from the tip. This pin' and the plates 45 also serve the useful purpose of preventing the lower portion of the flame spreader from burning .out as a result of the intense heat developed there by the burner flame.

In the modified form of heater, no provision has been made for pre-heating the incoming air since this is found neither necessary nor useful in this design of heater.

The amount of heat supplied by this modified form of heater may be regulated either by ad- Justment of the burner flame or by mixing the hot air from the outlet 23 with a variable amount of cold air from the outside. Such mixing with the outside air may 'be accomplished in a mixing chamber having a suitable valve for controlling the amount of cold air admitted. In this case, the suction fan 39 would, of course, be placed at the outlet of the chamber, rather than on the pipe 23. Such mixing chamber forms no part of my invention and is. therefore, not disclosed herein.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A hot air heater for supplying warm air to the interior of a room or other compartment comprising a cold air inlet pipe and a warm airoutlet pipe, each of said pipes being provided with flanges spaced inwardly from the outer ends thereof, and means for resiliently-and detachably securing said heater to the outer surface of the compartment wall with each of the above-mentained, a burner located in the bottom of said Jacket, a vertical flue joined to the top of said jacket, a hot air jacket spaced from' and surrounding. said fire jacket within which the air to be heated is confined, a horizontally disposed hot air duct joined to the upper end of said hot air jacket, a housing shell spaced from and surrounding said hot air jacket and a portion of said duct, a sealing ring encircling said duct and joined to said shell, a flanged mounting leg extending horizontally from the bottom of said shell. and means for resiliently and detachably securing said heater to the outer surface of the compartment wall with the hot air duct and mounting leg extending through holes provided in the wall for receiving the same.

3. A hot air heater for supplying warm air to the interior of a room or other compartment comprising a vertically disposed flre. jacket within which the products of combustion are con-' tamed, a burner located in the bottom of said jacket, a vertical flue joined to the top of said jacket, a hot air jacket spaced from and sur-- rounding said fire jacket, a horizontally disposed hot air duct joined to the upper end of said hot air jacket, a housing shell spaced from and sur-' for conducting the fluid to be heated through the interior of said flame spreader, a rod of heatconducting material located in a substantially vertical position within said flame spreader and projecting through and slightly beyond the lowermost portion thereof, and one or more plates of heat-conducting material located in a substantially horizontal position within the lower por-.

tion of said flame spreader and intimately joined thereto, said rod and said plates being effective to dissipate the heat collected by' the lower portion of said flame spreader to the fluid passing through the interior thereof.

5. The invention as defined in claim 4 wherein said plates are provided with perforations so as not to unduly interfere with the flow of fluid through the interior of said flame spreader.

WILLIAM H. RICHARDS.

provided 

